Structural characterization and continuous cellular automata simulation of micro structures by focused Ga ion beam induced deposition process

Abstract

Focused ion beam induced deposition (FIBID) is a high-resolution micro/nano fabrication technique with the injection of precursor gas to produce complex three-dimensional structures, which can be used to construct nanodevices. Due to the complex interaction between precursor gas, incident ions, and the substrate, the morphology of deposition structure dramatically depends on the process parameters. In this paper, based on the Continuous Cellular Automata (CCA) and the extended precursor molecule diffusion model (EPMDM), the effects of different process parameters on the final deposition morphology, are systematically studied. The experimental and theoretical work explores the relationship between the characterization of the deposition structure and process parameters. Considering the variation of diffusion effect intensity, the diffusion coefficient matrix decaying with the structure height is established to calculate the contribution of diffusion effect more precisely, which can also explain the non-uniform growth of deposition structure in the FIBID process. The vacuum surface cells (VSCs) and solid surface cells (SSCs) are recognized for deposition and sputtering respectively in the CCA, so as to trace the dynamic deposition contour, and reproduce the coexistence of deposition and sputtering phenomena. In order to verify the proposed CCA simulation model, micro pillar array and other structures are fabricated by focused Ga ion beam induced C9H16Pt precursor gas. The experimental and simulation results show that the proposed model can well simulate the morphology of deposition structures under a wide range of process parameters of dwell time, refresh time, ion beam current and pixel overlap. Therefore, the model can provide a good prediction method for parameter optimization of focused Ga ion beam induced deposition process.